method of producing various massive blanks of encapsulated pipe connections by virtue of powder moulding

ABSTRACT

The invention concerns a method of producing various massive blanks of encapsulated pipe connections by pressure moulding metal powder material, such as an encapsulated manifold ( 1 ) on a base plate ( 2 ). In an open mould of steel plates are installed a planned network of both curved and straight pipes ( 4 ) both for fluids, via a series of control valves ( 3 ) to a control module for hydraulic couplings, and for through pipes ( 5 ) for couplings for hydraulic and electrical distribution. From holes in the mould walls pipe ends are extending, which are sealed to the holes in the mould plates. External plates entered on to pipe connectors and locked before the HIP process hold the geometry of the piping network. When the network of pipe and cable connections is established, the top plate is sealed to the mould. A flexible steel bellows is fastened to the top plate, and is used to fill the mould with casting powder and for replenishing to eliminate volumetric shrinkage in the mould during the HIP process, whereafter the mould is removed, and the cast blank is machined before external pipe network and cable connections are connected.

The invention relates to a method of producing various massive blanks of encapsulated pipe connections by virtue of powder moulding, as stated in the introduction to the accompanying claim 1.

In production of units for among other things distribution of hydraulic liquid in control valve manifold and base plate for control modules, also for under water use, there is as of today no alternative to so-called long hole drilling.

Problems/drawbacks with long hole drilling are:

-   -   High production cost.     -   Demanding machining with risk of rejects.     -   Poorer flow conditions for the hydraulic liquid through straight         channels.     -   Pockets, where dirt can gather.     -   Today's design causes manifold and base plate to be produced         separately, giving an interface between manifold and plate with         appurtenant seals for the hydraulic runs.     -   There are limitations in the design of the equipment tied to         geometry and positioning of components.

Long hole drilling of manifolds and base plates has been utilised all the time since production of subsea control modules started. Hughes Aircraft had, in the 1980′s, a special technique of laminating base plates with channels on their subsea control modules. The company went off the market at the end of the 1980′s, and nobody carries out such work today.

The objective of the invention is to bring about a competitive product such as:

-   -   Reduced production cost.     -   Simplified machining allowing more participants with shorter         delivery times.     -   Reduced production time.     -   Improved flow conditions for hydraulic liquid through curved         channels.     -   No pockets where dirt can gather.     -   Manifold and base plate are integrated thereby avoiding         interface thereinbetween, and in addition reduction of number of         potential leak points.     -   Larger freedom in design of equipment geometry and positioning         of components.     -   Volume and weight reduction.     -   Simplify offering of manifolds having many functions, where         reserve functions can be blinded.

The present application relates to a method of producing various massive blanks of encapsulated pipe connections by virtue of powder moulding, the method being characterised by the features set forth in the claims.

FIGS. 1A-1D shows part of the arrangement partly in section and viewed from the side, from above and in 3D, forming manifold 1 and base plate 2, with details of piping 4 and sleeves 5 in the transition between base plate 2 and manifold 1. The arrangement is shown before an enclosing mould is filled with metal powder, which undergoes a HIP (Hot Isostatic Pressing) process. The internal piping 4 will later be channels in the blank. The manifold 1 and the base plate 2 are made as a continuous part, and the channels shall go through these parts.

With prior art the manifold and the base plate are separate parts being put together. The base plate becomes the lower part of a completed control module and is mounted on an appurtenant plate including electric and hydraulic connectors, which are connected to hydraulic and electric distribution on a subsea installation.

The manifold portion 1 of the control valves 3 being left within a subsea control module in its final employment is not shown full height in the drawing. Typically ten control valves 3 may be positioned side by side upwards along two of the manifold's 1 sides. Future positioning of three hydraulic control valves 3 on the manifold 1 is included to illustrate this. On top of the mould a metal bellows, not shown, is positioned for control of the material shrinkage. This and the pipe ends extending from the blank after the finished HIP process are removed from the blank in connection with machining of the manifold 1 and the base plate 2.

The drawings show through piping 5 placed in a circle in the base plate 2, where the electrical connectors will be in the finished machined blank. Hydraulic outlets are placed in the base plate in a circle inside the electric connectors, and these are connected with a series of positions for future valve ports on two sides of the manifold 1 via internal piping 4 establishing the conduits for the hydraulic liquid. To illustrate how the control valves 3 shall be placed on the finished machined blank, these are also shown on three of the FIGS. 1B, 1C and 1D.

FIG. 1A shows side view of the lower part of the manifold 1 mould and the base plate 2 mould. The internal piping 4 in the mould forming the manifold 1 is shown, and pipe connections extend from the plates forming the outside mould of the base plate 1 and manifold 2. The pipes are open ended, while the openings between the pipe throughputs in the plates and the pipes are seal welded.

FIG. 1B is rotated 90° relative to 1A, and shows the outside of the base plate mould. Uppermost on the part of the manifold 1 shown, two groups of holes can be seen where the pipes end up. These holes become hydraulic ports for the control valves 3. The control valves 3 are included in the drawing to show how these will be mounted on the finished machined blank.

FIG. 1C shows a top view of manifold 1 and base plate 2, with a section through the top of the base plate 2 with two of the larger through pipes 5 for electrical couplings placed vertically in an outer circle on the base plate 2. These may also be seen on the 3D FIG. 1D. The drawing also shows routing of pipes from various positions on the manifold 1, vertically down through the centre of the manifold 1 and a distribution of these out to the hydraulic outlets in the base plate 2 being placed in a circle inside the electrical throughputs.

FIG. 1D shows a partially sectioned 3D drawing of the manifold 1 and the base plate 2. The details are explained for FIGS. 1B and 1C. The figure gives a better illustration of how the pipes are bent to give optimal flow conditions in the future channels. Uppermost on the manifold plate and the base plate 2 are seen the through pipes 5 and the pipes 4 which are welded to the plates. Future positioning of control valves 3 after machining are also shown.

The object of the invention is to establish in advance conduits by means of both curved and straight pipe connections for distribution of hydraulic liquid between couplings in the base plate 2 and ports for control valves 3. Straight through pipes 5 also pass through the base plate 2. These conduits are later machined for mounting of electrical connectors. The pipe connections are encased in a mould being filled with powder forming an encasing blank when powder moulding, such that the pipes form integrated flow channels for fluids such as hydraulic liquid in a machineable blank, or form starting points for further machining of throughputs for electrical connectors.

The encasing blank is produced by means of prior art, Hot Isostatic Pressing—HIP, from metal powder materials. The blank is produced by filling a mould with powder being placed in a container and heated under vacuum conditions to remove oxygen and moisture from the powder.

The container is sealed and the HIP process is carried out at high inert gas pressure and high temperature, 1000° C. Internal voids are filled and a homogenous, compact material is obtained having higher strength than comparable forged material.

A mould is welded together from steel plates with for example laser cut holes to place the pipes through, and the mould represents the finished blank external sides. The mould is open to make access, while the pipe network 4 to the control valves is made. When the pipes are installed, the mould top and side plates without throughputs are put in place and welding seals the mould. Pipe ends will then extend from the holes in the mould. Welding also seals the openings between these holes in the plates and the pipe ends, while the pipes themselves remain open. On top of the mould is welded a flexible steel bellows serving as an external riser.

The mould is filled with powder and the steel bellows is stretched out and topped up with powder, as it shall take up and control the volumetric shrinkage during the HIP process, so that the blank itself is not affected.

To maintain the geometry between the pipes 4 forming interface towards the valves on two of the finished machined manifold 1 sides, the pipes 4 are kept in place during the HIP process using external plates of a ceramic material with the same hole pattern as the plates in the mould. The external plates are entered onto the pipe connections and interlocked in the correct position. Following the HIP process, the external plates are removed and reused in the next process. 

1. A method of producing various massive blanks of encapsulated pipe connections by Hot Isostatic Pressing—HIP of metallic powder material, to a capsulated manifold on a base plate, characterised in that in an open mould of steel plates are installed a planned network of both curved and straight pipes (4) both for fluids, such as hydraulic liquid, via a series of control valves (3) to a control module for hydraulic couplings, and for through pipes for electrical couplings, being connected t hydraulic and electrical distribution, from holes in the mould walls ends of pipes and through pipes extend, the ends being sealed to the holes in the mould plates, to keep the geometry between the pipes these are held in position by means of external plates entered on to the pipe ends and locked before the HIP process, when the planned network of pipe and cable connections is established, the top plate is sealed to the mould, and to the top plate is fastened a flexible steel bellows used to fill and to replenish the mould with casting powder to eliminate volumetric shrinkage in the mould during the HIP process, whereafter the mould is removed and the cast blank is machined before connecting external pipe network and cable connections. 